Electrical safety switch



Dec. 27, 1949 W H UNDAE 2,492,490

ELECTRICAL' SAFETY SWITCH Filed Aug. 22, 1945 4 She'ets-Sheet l Y FIG 16/N VEA rox? WILLIAMv H. LIN DAE A ay,

Dec. 27, 1949 w. H. LINDAE ELECTRICAL SAFETY SWTCH 4 Sheets-Sheet 2Filed Aug. 22, 194e mwx /NVEN-/fo WILLIAM H. I moAE /97- To RA/EY Dec.27, 1949 w. H. LINDAE 2,492,490

ELECTRICAL SAFETY SWITCH Filed Aug. 22, 194e 4 sheets-sheet s Dec. 27,1949 w. H. LINDAE 2,492,490

ELECTRICAL SAFETY SWITCH Filed Aug. 22, 194e 4'sheets-sheet 4 FIG.10.

/N VEA/roze WILLIAM H. I nNoAE Patented Dec. 27, 1949 ELECTRICAL SAFETYSWITCH William H. Lindae, St. Louis, Mo., assigner of one-half to EolaLndae and one-half to Joseph P. Pohrer Application August 22, 194.6,Serial No. 692,342 Y 11 Claims.

This invention relates in general to certain new Iand usefulimprovements in electrical safety switches. Electrical safety switchesare widely used in industrial applications. The usual type is in itsessence a double-pole, single-throw knife switch, with a cartridge-typefuse incorporated in each leg of the circuit, a protective case, and an.operating handle outside the case. It is necessary to open theprotective case of such a switch in order to remove and replace fuses.When so opened, the switch is no longer safe. Short circuits are readilycaused by the insertion of metal lic tools, and workmen servicing suchswitches are frequently injured as a result of accidental contact withthe current-conducting portions inside.

The primary object of this invention is to provide a switch containingfuses which may be readily changed with `complete safety.

A further object of this invention is to eliminate the conventionalswitch blades and to utilize the ordinary knife-blade, cartridge-typefuses as the movable elements of the switch.

A lfurther object of this invention is to provide a safety switch boxwith an access door which can be opened only when the fuses are indisconnected position, and then sufliciently for access to the fusesonly.

A further object of this invention is to provide a switch-operatingdevice having positive action with a springboost, quick make-'and-breakmechanism.

The above and other objects will become more fully apparent from thefollowing specification which, by way of illustration rather thanlimitation, shows preferred processes and preferred forms of apparatusconstituting embodiments of the present invention, the scope of which isdefined in the appended claims.

In the accompanying drawings- Figure 1 is a perspective View of a safetyswitchl constructed in accordance with and embodying my presentinvention;

Figure 2 is a horizontal sectional view taken along line 2 2 of Figure1, and showing the switch mechanism in disconnected position;

Figure 3 is a vertical sectional view taken along line 3 3'of Figure 2;

Figure 4 is a fragmentary top view, partly in section, taken along line4 4 of Figure 3;

Figure 5 is a fragmentary top View, partly in section, taken alongV line5 5 oi Figure 3;

Fig-ure 6A isa transverse view, partly in section, taken along line 6 6ofv Figure 2with the switchl in disconnected position, showing in dottedlines the open position of the access door and a fuse being removedthrough it;

Figure 7 is a view along the same line as Figure 6, with the switchconnected;

Figure 8 is a. fragmentary sectional View along line 8 8 of Figure 7;

Figure 9 is a fragmentary View along line 9 9 of Figure 2, showing theswitch mechanism in disconnected position, but with the access doorlocked;

Figure 10 is a view similar to Figure 9 showing the switch mechanism indisconnected position and the operating lever thrown into position foropening the access door;

Figure 11 is a view similar to Figure 9 showing the switch mechanism inso-called dead center position;

Figure 12 is a view similar to Figure 9 showing the switch mechanism infully closed position;

Figure 13 is a View similar to Figure 9 showing the switch mechanism indead center position preparatory to breaking the circuit;

Figure 14 is a fragmentary sectional view along line I 4-I 4 of Figure9;

Figure 15 is a fragmentary sectional view along the line I5--I5 ofFigure 9;

Figure 16 is a fragmentary sectional view along line IB |6 of Figure 9;and

Figure 17 is a schematic view of a modified form of safety switchconstructed in accordance with and embodying the present invention.

Referring now in more detail and by reference characters to the drawingswhich illustrate a preferred form of the present invention, A desighatesa safety switch comprising an cuter shell or box a, including arear-wall forming dielectric base I, side walls 2, a top wall 2', abottom wall 2", and a transparent plastic front panel 3 removablysecured in place by screws 4. The top and bottom walls 2', 2" arerespectively provided adjacent base I with upper and lower connectionapertures 5, 5" and one side wall 2 is provided upon its opposite facewith axially aligned side bearing collars 6 for rotatably supportingshaft 'I which extends horizontally therethrough and at one extended endis provided with an operating handle 9 secured thereto by a set-screwI9.

Formedv in the base I are apertures II for receiving bolts I2 attachedthereto by nuts i3 and adapted to hold in place upper and lower contactblocks I4 which are suitably tapped to receive binding posts I5 wherebybuss-bars is lmay be connected to the switch. Similarly attached to theinsulating base I at mid-height are journal brackets 29, which extendforwardly into the box d and have bearing apertures 2| aligned with thehorizontal axis of shaft l. Rotatably mounted in the apertures 2| arejournals 22 extending from rotary side frames 23, which are tapped toreceive screws 24 mounting thereto front insulating fuse plate 25 andrear insulating fuse plate 26, provided with relatively large apertures2l serving as supports and guides for cartridge-type fuses 28 havingknife-blade ends 29. Fuse stopplates 39, attached by screws 3| to rearinsulating fuse plate 26, prevent fuses 28 from being inserted too far,and contain slots 32 which vertically align the knife-blade fuse ends29.

Aixed to the upper and lower contact blocks |4 are, respectively, uppercontact clips 33 and lower contact clips 34, each of which has a pair ofvertical parallel .blades 35 provided with inwardly-embossedspherically-rounded contacts 36 containing at their contact surfacessilver inserts 31, aft of which is lateral bolt 38 and nut 39 under theheads of which are radially-split spring washers 40. Lower contact clips3d have similar vertically parallel blades til with inwardly-embossedspherically-rounded contacts 42 containing similar silver contactinserts 3l, forward of which are lateral bolts 43, nuts 39, and radiallysplit spring washers 40. Contacts 36 and 42 are vertically above andbelow, respectively, the axis of journals 22, and at the same radialdistance therefrom. The shanks of bolts 38 and 43 serve as stops for theknife-blade fuse ends 29 when fuses 28 are in vertical or connectedposition. Thus, fuses 28 center upon the axis of rotation of journals 22and may be rotatively engaged with said contact clips by turning in thedirection indicated by arrows in Figure 6 and may be disengagedtherefrom upon rotation in the opposite direction.

To prevent arcing of the contacts 39 and 42 and to hold the fuses 28 inproper position within the fuse-plate apertures 21 during the operationof the switch, each upper contact clip 33 is provided with a guide plate45 having a contact end 46 bent into the arc of rotation of the upperknife blade terminal 29, and at its other end is provided with a tongue4l which projects between blades 35 and rests upon a pin 4B, the latterbeing mounted in and projecting through the blades 35 and being providedin its projecting ends with diametral apertures 49 for receiving theends of wire spring U which, at its outer end extends across and bearsupon the upper surface of guide plate 45 and intermediate its ends iscoiled on each side of blades 35, around the ends of pin 5| projectingthrough blades 35. For the same purpose each lower contact clip 34 isprovided with leaf spring 52 having a rear portion 53 extending upwardlybetween blades 39 in the formation of a blade guide and initialcontact,- the forward end 54 of the spring 52 being bent upwardly andsecured by screws 55 to block 55 mounted between blades 39 on bolt 42.

It will be understood that all portions of the switch which are intendedto conduct the current are fabricated of copper or other metal havinggood electrical conductivity as in case of contact block I4, contactclips 33 and 94, guide platos 45, andleaf springs 52. Y

From rotary side frame 23 on the side jacent to operating handle 9,operating pin 5i projects laterally, its axis being parallel to, but notcoincident with, the axis of journals its rotary travel about said axisis limited by upper arcuate stop lobe 58 and lower arcuate stop lobe 59formed in both reinforcing plate 99 and in the forward-projecting end ofthe adjacent journal bracket 2B, to which plate 59 is spotwelded.

Operating pin 5l projects also through, and is .in the several stages ofoperation engaged from time to time by, the driving cam Si keyed to theinner end of shaft 'i and held by retaining screw 62 and is also engaged,by iioating cam 63 which is, in turn, rotatably mov on shaft 1.Functional portions of the di cam El include its arcuate lobe C55 at thehead of groove 65, outer or door-control, face E9, and door engagement5l. The driving cam also provided with a laterally projecting pin whichmoves between the inner arcuate lobes 6i) and 'lll of floating cam 63.The floating cam 93 is nally provided with outer arcuate lobes l! and i2adapted to engage operating pin 5i' in the operation of the switch ashereinafter described. Fixed upon floating cani 53 is a lateral pin i3on which pivots the lower end 'ill of the rod '55, the upper end ofwhich is threaded to receive nut l5. Beneath said nut 'it rod 'l5 passesthrough sleeve 'il swivel-mounted by its stud i8 to the side adjacentwall 2 of box a by means of nut 19 and washer B9. Fitted over red 'i5between lts lower end lil and sleeve "il is a spiral spring 8i.

The front panel 3 of safety box a is provided with circular openings 82so located that when the switch is in disconnected position, frontinsulating fuse plate 25 will be presented toward said openings, withthe fuse plate apertures El in registration therewith, permitting theremoval and replacement ci fuses it will be noted access to the interiorof the boxes is prevented beyond that suflicient ior fuse removal.Mounted on the face panel 9 adjacent to the lower edge of the opening 32are hinges t3 for operatively supporting the outwardly opening accessdoor 84, provided with an inwardly-extending lever 85 with flange 85whose upper 8l bears against the door-control face 5t of driving cam 6iexcept when the mechanism is in extreme disconnected position as inFigure l0. In such position the door dri can be opened, and the loweredge @il of flange CIBG wil] ,be engaged by notch El in cani 9i, asshown in Figure 6,

and so held by force of gravity on the handle 9.-

When iiange 86 is released from the notch the door 84 is retained closedby tension spring 89 connecting stud 9|) cn door lever B5 with lug 9|aiiixed to the base ci box c by rivet When connected, the respectiveparts of the operating mechanism are in positions shown in Figure 12,except that the operating handle 9 may be moved upward and aft to apoint slightly beyond center so that driving cam lobe 54 rests againstoperating pin 5l. In order to break the circuit, the handle 9 is broughtforward and down about a half turn to approximately vertical position sothat pin 9S engages lobe of the floating cam, bringing the spring drivenrod T5 past the dead-center position shown in Figure 13. The resultingcompression in spring Sli drives the floating cam 63 so that its outerlobe 'i2 engages operating pin 5l and forces it against the lower stoplobe 59. rihe 90 travel of the operating pin 5l eilects a correspondingrotation or" the fuses 28, bringing their upper knife-blade terminals'29 forward and down out of engagement with upper contact clips 33 andguide plate 46, and their lower terminals 29 aft and upward out of 5engagement with. lower Contact clips 3.4; and. their contact. springs52, so fuses llt.v assume the, horizontalposition showny in Figure 6;However, with the operating handlevertica-lly dow-n, access door cannotbe opened because cam face 66 bears against upper edge 81 of the doorlever ange 86'. When the lever is swung farther forward as shown in.Figure 10, the-door may be opened as shown in Figure 6, and the resesrremoved andA replaced. It is to' be noted that the opening 82' in thefront face 3 of' safetyI box 2 isrelatively small, and whenever the doorcan be opened front insulating fuse plate itis presented closely infront of it, making it almost impossible for the person removing theswitch to touch any part inside the box other than this plate and thedisconnected fuses. In this manner the job of changing fuses is renderednon-hazardous.

It is apparent that until the access door is closed, the switch cannot.be connected. Upon closing the door the handle returns by gravity to theposition shown in Figure 9, pin 68. engaging inner lobe 'Hlv of thefloating cam. The handle is brought outward and'. upward past thedeadcenter position shown in` Figure 11. Before reaching thisposition,lobe 64 of the driving cam has already raised the operating pin 51 fromlower stop lobe 59, After the dead-center has been passedv however, thecompression in. spring 8l drives outer lobe 1| of the iloating camagainst operating pin 5l,` carrying it up and against the upper stoplobe, 5 8, rotating the fuses into vertically upward position and thusmaking the circuit.

The mechanism shown makes and breaks the circuit positively and'withextreme rapidity, The use of guide plate 45 on the upper contact, andleaf springt 52 onV the lower assures that arcing cannot Wear awayv thespherically-rounded upper and lower contacts36 and 42, or theirlong-weare ing silver inserts 31.l

A modified form of safety switch A' may also be provided, as shown inFigure 17', and is substantially identical in all its mechanical partswith the previously described safety switch A except that the' outgoingleads 93', which are normally deadwhen` the switch is disconnected, areprovided with a small many-turned induction coil 94, the ends of whichare connected directly across the terminals of a small ruby lamp 95which may be either of' the incandescent or fluorescent type as desired.Thus, when current is iiowing through the outgoing leads 93 the lampswill glow, providing an indication of suoli` fact. When the switch A isdisconnected and current ceases.

to. flow in the leads 93, the lamp. 95 will go out. If, for any reason,the mechanical parts. of the switch A' should malfunction and tail todfi-,S-

connect properly even though the handle and relatingl mechanism havebeen moved into disconnecting position, this failure to disconnect willbey l. operating mechanism for a safety switch inbearing penetrating theside ofthe switch box,

and ashaft rotatably mounted therein on an.

axisl concentric with that of said rotating switch element, saidoperating mechanism comprising an operating lever lined` to the outerextremity of said. shaft, a cam keyed to the inner end of the operatinglever and having an outer face, an access door control mechanismabuttingsaid facel whereby to permit opening of an access door only when saidoperating lever is, in position for dis. connection of the circuit, a.second cam mount.- ed on said shaft adjacent to said first named cani,`spring means carried by the switch box and acting eccentrically ori saidsecond cam in a plane substantially parallel to. its plane of rotationthereby permitting travel on each side of a deadcenter position of saidspring means equal to not less than the arc of rotation, a pin eccentricand parallel to the axis of rotation of said rotating switch elementinterconnecting it with lobes of 3 ist saidl second cam during travelthrough the arc of rotation in either direction after pass-ing saidVdead-center position, so that the spring force released as said positionis passed will drive said rotating switch element through said arc of'rotation, stop means limiting rotary travel of the switch element to theare of rotation, and a pin operating between cam lobes, interconnecting.

said nrst named cam with said second cam during travel of said secondcam in either direction approaching and passing the dead-centerposition.

2.- In a safety switch, spaced'xed contact elements, af rectangular fusecarrying frame inf p minal of the fuses, and. means for rotating saidrectangular frame sor as to optionally engage and disengagey the endterminals with the iixedV contact elements.

3. In a safety switch, spaced fixed contact elements,v a rectangularfuse carrying frame includingk forward and rear insulating plates havingaligned apertures, said frame being journaled for rotation about, anaxis lying between said contact.

elements,.cartridge fuses supported in said apertures and. having endterminals extending therethrough, fuse stop plates secured to saidlinsulating fuse plates to limit movementy of the fuses through saidapertures, said stop plates having slots disposed in a plane at rightangles to the yaxis of rotation of the fuse carrying .trame throughwhich extend one end terminal of thel fuses, and means for rotating saidrectangular frame so a-s toioptionally engage or disengage the -endterminals with the fixed contact elements.

4; In a safety switch,v vertically spaced lxed Contact elements, arectangular fuse carrying frame including forward and rear insulatingplates having aligned apertures, said frame being Qjournaled' forrotationy about an axis lying between saidl contact elements and' insuch ainan-4 ner that. saidl forward plate will be positionedhorizontally and: above said axis and the rear plate will be positionedhorizontally and below- "said axis when the'V switch is in closedposi-tion,-

7, cartridge fuses loosely held in said apertures and having endterminals extending therethrough, fuse stop plates secured to said rearinsulating fuse plate adjacent the apertures in said rear plate toprevent movement therethrough of the fuses when said fuse carrying frameis rotated to closed position, said stop plates having slots disposed atright angles to the axis of rotation of the frame through which extendone end terminal of the fuses, and means for rotating said rectangularframe so as to optionally engage and disengage the end terminals withthe iixed contact elements,

`5. In a safety switch, vertically spaced contact elements, a lingerelement extending outwardly from the upper one of said fixed contactelements, a rectangular fuse carrying frame including forward and rearinsulating plates having aligned apertures, said frame being journaledfor rotation about an axis lying between said contact elements and insuch a manner that the forward plate will be positioned horizontallyabove said axis and the rear plate will be positioned horizontally belowsaid axis when the switch is in closed position, cartridge fuses looselyheld in said apertures and having end terminals extending therethrough,fuse stop plates secured to said rear plate adjacent the apertures insaid rear plate to prevent the fuses from falling therethrough when theframe is rotated to closed position, said stop plates having slotsdisposed in a plane at right angles to the axis of rotation of saidframe through which slots extend one end terminal of the fuses, theother end terminal of said fuse engaging said finger element on theupper fixed contact element when the frame is rotated into circuitclosing position whereby said fuse is firmly seated upon said fuse stopplate insuring complete contact between said end terminals and said xedcontact elements, and means for rotating said rectangular frame so as tooptionally engage and disengage the end terminals with the fixed contactelements.

6. A safety switch comprising pairs of substantially vertically spacedstationary contacts, a frame journaled for rotation about asubstantially horizontal axis located intermediate the contacts, andbeing adapted to move from a horizontal to a vertical position, saidframe having aligned apertures, a cartridge fuse loosely disposed withinsaid apertures and being freely removable from the frame when the latteris in horizontal position, said cartridge having blade-like terminalmembers adapted for contactive engagement with said contacts when theframe is in vertical position, and resilient guide plates mounted uponthe stationary contacts for slidably engaging the transverse end facesof said terminal members as the frame is rotated into vertical positionfor restraining the cartridge fuse against endwise movement in relationto the frame.

'7. -A safety switch comprising vertically spaced contact elements, aiinger element extending outwardly and downwardly from the upper one ofsaid contact elements, a nger element extending upwardly and outwardlyfrom the lower one of said contact elements, a rectangular fuse carryingframe including forward and rear insulating plates having alignedapertures, said frame being journaled for rotation about an axis lyingbetween said contact elements and in such a manner that the forwardplate will be positioned horizontally and above said axis and the rearplate will be positioned horizontally and belowsaid axis when the switchis in closed position,

cartridge fuses loosely held in Said apertures and having end terminalsextending therethrough, fuse stop plates secured to said rear plateadjacent the apertures in said rear plate to prevent the fuse fromfalling therethrough when the frame is rotated to closed position, saidstop plates having slots disposed in a plane at right angles to the4axis of rotation of said frame through which slots extend one endterminal of the fuses, the end terminals of said fuses engaging saidfinger elements on said iixed contact elements when the frame is rotatedinto circuit closing position, lwhereby said fuses are rmly seated uponsaid fuse stop plate and insure complete surface contact between saidend terminals and the xed contact elements, and means for rotating saidrectangular frame so as to optionally engage and disengage the endterminals with the xed contact elements.

8. An electric switch comprising a rectangular fuse carrying frame,cartridge fuses with end terminals supported in said frame, the endterminals of said fuses protruding through apertures in said frame,spaced fixed contact elements, said frame being journaled for rotationabout an axis lying between said contact elements, means for rotatingsaid rectangular frame s0 as to optionally engage and diseng-age the endterminals with the xed contact elements, said contact elementscomprising a pair of parallel blades, said blades provided with inwardlyembossed spherically rounded contact points, resilient guide plates 35mounted on said blades and extending outwardly from said blades into thearc of rotation of the end terminals, a tongue provided at the extremeouter end of said resilient guide plates to make initial contact withsaid end terminals when said switch is rotated into circuit closingposition, and spring members provided on said contact elementsI tomaintain said guide plates to said blades.

9. An electric safety switch comprising a rec- 45 tangular fuse carryingframe, cartridge fuses with end terminals loosely held in said frame,said frame having apertures through which said end terminalsprotrude,vertically spaced fixed contact elements, said frame being journaled forI0 rotation about an axis lying between said contact elements, saidcontact elements comprising a pair of parallel blades, said uppercontact elements having a first resilient guide plate member extendingoutwardly and downwardly therefrom, U said lower contact elements havinga second resilient guide plate extending upwardly and inwardly therefromwhereby said fuses are seated securely within the apertures of the frameby a downward action of the first resilient guide plate l on one endterminal of the fuse and an upward movement of the other end terminal bythe second resilient guide plate when said fuse is rotated into circuitclosing position thus insuring complete contact between said endterminals and said .I contact elements.

10. In an electric safety switch of the type wherein the circuit is madeby rotating a fuse carrying frame through which the end terminals of thefuses protrude through a fixed arc of rotation less than 180 intocontact with electrical contacts opposed at a distance corresponding tothe fuse length between terminals and breaking said circuit by rotatingsaid fuse carrying frame through said arc in the opposite direction, aprotective case, an access door in said case adjacent to one end of saidfuse terminals when in disengaged position, a bearing extending throughthe side of said case, a shaft rotatably mounted therein on an axisconcentric with that of said fuse carrying frame, an operating handlefixed to the outer extremity of said shaft, a cam keyed to the inner endof said lever and having an outer face, access door control mechanismabutting said face whereby to permit opening oi said access door onlywhen said operating handle is in position for disconnection of thecircuit, a second cam mounted on said shaft adjacent to said rstmentioned cam, spring means attached to said iixed insulated portion andacting eccentrically on said second cam in a plane substantiallyparallel to its plane of rotation, permitting its travel on each side ofa dead center position oi said spring means equal to not less than thearc of rotation, a pin eccentric and parallel to the axis of rotation ofsaid fuse carrying frame interconnecting such frame With lobes of saidsecond cam during travel through the arc of rotation in either directionafter passing said dead center position so that the spring forcereleased as said position is passed will drive said frame through saidarc of rotation, stop means limiting its rotary travel to the arc ofrotation, and mechanism, as a pin operating between cam lobes,interconnecting said rst cam with said second cam during the latterstravel in either direction approaching and passing said dead centerposition.

11. In an electric safety switch of the type wherein the circuit is madeby rotating a fuse carrying frame through which the end terminals of thefuse protrude through a fixed arc of rotation less than 180 into contactWith electrical contacts opposed at a distance corresponding to the fuselength between terminals and breaking said circuit by rotating said fusecarrying frame through said arc in the opposite direction, a protectivecase, an access door in said case adjacent to one end of said fuseterminals when in disengaged position, said access door being hingedlymounted on an axis parallel with the axis of rotation of the fusecarrying frame, a lever attached to said door and extending Within theprotective case, a ange provided on said door lever, a bearing extendingthrough the side of said case, a shaft rotatably mounted therein on anaxis parallel to the hinge axis of the access door, an operating handlefixed to the outer extremity of said shaft, a driving cam keyed to theinner end of said shaft and provided with a cutaway portion `along itsperiphery, said driving cam co-operating lwith means for operativelyrotating said fuse carrying frame, the ange of said door lever abuttingagainst the periphery of said driving cam When the rotatable fusecarrying frame is in circuit closing position whereby opening of thedoor is prevented, the ange of said door lever being opposite thecut-away portion of said driving cam for opening of said door when thedriving cam is so moved as to rotate the fuse carrying frame intocircuit breaking position.

WILLIAM H.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 756,541 Sorensen Apr. 5, 19041,300,546 Armstrong Apr. 15, 1919 1,364,977 Brillhart Jan. 11, 19211,534,515 Getchell Apr. 21, 1925 1,604,191 Palmer et al Oct. 26, 19262,007,634 Broadwell July 9, 1935 FOREIGN PATENTS Number Country Date188,820 Great Britain Nov. 23, 1922 266,110 Great Britain Feb. 24, 1927

